Trench digging machine



1961 c. J. DAVIS 2,997,276

TRENCH DIGGING MACHINE Filed Aug. 7, 1959 2 Sheets-Sheet l INVENTORCHARLES J DAVIS Aug. 22, 1961 c. J. DAVIS 2,997,276

TRENCH DIGGING MACHINE Filed Aug. 7, 1959 x 2 Sheets-Sheet 2 INVENTOR442 CHARLES J DAVIS ATTORNEY United States Patent 2,997,276 TRENCHD-IGGING MACHINE Charles J. Davis, 22 Colonial Court, Wichita 8, Kans.Filed Aug. 7, 1959, Ser. No. 832,200 4 Claims. (Cl. 254166) Thisinvention relates to an improved endless chain type trencher or trenchdigging machine.

It is an important object of the invention to provide a small, portable,simply constructed winch line propelled machine as opposed to large geardrive propelled machines.

It is another object to provide a trencher which does not require askilled operator because it is self-guided by means of its winch line orcable. It therefore requires only the proper placing of cable guidestakes along the desired path of travel, or the re-locating of the winchline anchor from time to time in order to dig a trench along the exactpath desired.

It is an additional object to provide a trencher of the type mentionedin which the winch drum is rotated by a ratchet wheel and levermechanism rather than by gears. Such mechanism can be set to propel thetrencher along the ground at any selected one of a number of differentspeeds. The machine can thus adapt itself to various digging conditions,such as ground hardness variations, ground moisture variations, depthand width of trench being dug, etc.

Additional objects are to provide a trencher which has a screw typeself-locking digging depth control which permits a change in diggingdepth while the machine is in operation; which is capable of digging atrench around fixed objects or obstacles without attention from theoperator, thus leaving the operator free for other tasks; which lays theearth dug in a neat windrow along one side of the trench, making thebackfill job easy; and which is so constructed that the endless chaintype digging unit can be raised to a position above ground level topermit the entire trencher to be easily moved manually from place toplace.

The invention, together with other objects, will be more clearlyunderstood when the following description is read in connection with theaccompanying drawings, in which:

FIG. 1 is a side elevation of a trench digging machine embodying myinvention;

FIG. 2 is a top plan view of the machine;-

FIG. 3 is a perspective view of a cable slide which constitutes a partof the guiding mechanism for the machine;

FIG. 4 is a fragmentary perspective view with parts in phantom, andillustrates the ratchet wheel and winch driving mechanism of themachine;

FIG. 5 is a side view of a latch for locking the combination directionalguide and handle for the machine in an elevated position;

FIG. 6 is a side elevation, with parts in section, of the mechanism foradjusting the depth of the trench to be dug by the digging unit; and

FIGS. 7 and 8 are schematic views of the ratchet wheel drive mechanismfor propelling the machine along the ground.

Referring to the drawings my trencher includes a chassis having a rigidframe designated as a whole by the numeral 1% and preferably made ofheavy steel plates welded together. The trencher has two wheels 11 and12 journaled at the forward end of the frame, and a single trailingwheel 13 at the aft end.

A winch drum shaft 14 is journaled transversely near the forward end ofthe frame. A driven shaft 15 is journaled transversely near the aft endof the frame.

A power unit 16, here illustrated as a gasoline engine, is connected todrive the driven shaft 15 through a conventional, geared speed-reducingtransmission 17. The unit is so constructed, however, that an electricalmotor can be interchanged with the gasoline engine for driving theentire unit.

An endless chain type trench digging unit is designated as a whole bythe numeral 18. It includes a rigid boom 19 which journals sprocket 20at its outer end. An endless chain 22 is carried by sprocket 20 andsprocket 21, the latter being keyed on drive 15. The chain carriesearth-cutting knives 23.

As a means of supporting the digging unit on the chassis '10 the boom isadjustably connected near its inner end, by means of bolts 24 and 25, toone arm of a bell-crank lever 26. This lever is journaled for freerotation about driven shaft 15 by means of a heavy bearing 27 (FIG. 5).

The other arm of the bell crank lever 26 is pivotally connected to oneend of an internally threaded rigid link 28, the other end of whichreceives a similarly threaded screw 29. The other end of screw 29 isjournaled in bearings 30 and 31 in the frame 10. The journaled end ofscrew 29 is keyed to a crank 32. By means of this crank the boom 19 andthe entire earth-digging unit can be moved pivotally about the drivenshaft 15 between the solid line position shown in FIG. 1 and the dottedline position '33. An auger blade (FIG. 2), designated as awhole by thenumeral 63 is fixed on one end of drive shaft 15 immediately adjacentthe digging unit chain 22, and serves to move the earth dug by the unitslightly to one side, and to deposit it in a neat windrow alongside thetrench being dug.

As previously mentioned my trencher is propelled slow- .ly along theground as the trench is dug by means of a winch line or cable 34. Oneend of the cable is attached to a stake or ground anchor (not shown) andthe other end of the line is attached to a winch drum 35 (FIG. 2) whichis carried by and rotateswith the shaft 14. At its forward end mytrencheris equipped with a combination directional guide and handle 36for the machine. The guide 36' is generally U-shaped and its free endsare pivotally mounted on the front end of the frame 10. When thetrencher is in operation the guide 36 is lowered to the position shownin FIG. 1 and cable 34 extends through a slide 37 carried by the forwardend of the guide member. The slide 37 is shown in detail in FIG. 3.

When the machine is to be moved from one location to another, the cable34 is reeled on to the drum and the guide member or handle 36 is raisedto the dotted line position 38, FIG. 1. A pair of latches 39 (FIG. 5)are pivotally mounted on the front end of the frame 10 on a common axis40 and engage a transversely projecting pin 41 on each leg of the handle36 to lock the handle in the elevated position.

As a means of slowly rotating winch drum 35 to reel in cable 34 to pullthe trencher along the ground, a ratchet wheel and lever mechanism isused. This mechanism is clearly shown in FIG. 4, and its operation isillustrated in FIGS. 7 and 8.

The mechanism includes a ratchet wheel 42 which is keyed on shaft 14 toforce rotation of that shaft as the ratchet wheel is rotated. A camlever 43 has one of its ends journaled for free oscillation on the winchshaft 14, and its free end extends radially outward in a plane common tothe plane of a cam 44 which is keyed on driven shaft 15. As shaft 15rotates the cam 44 forces oscillation of lever 43. Intermediate its endslever 43 carries a ratchet pawl- 45 which is pivotally mounted thereonby means of a pin 46. Pawl 45 also carries a pin 47 the purpose of whichwill be explained.

A holding pawl 45 is pivotally mounted on a fixed pin 49 supported onthe frame 10. Pawl 48 also carries a pin 50. Movement of the two pawlsis coordinated by means of a link 51 one end of which is pivotallyconnected to pawl 48 by the pin 50, and the other end of which isslidably connected to pawl by means of an elongated slot 52 throughwhich the pivot pin 47 extends. A tension spring 53 has its oppositeends connected to the pawl carried pins and 47, respectively, and urgesthe pointed ends of each of these pawls into contact with the teeth ofthe ratchet wheel 42. An additional spring 54 has one end connected tothe pin 46 and its opposite end connected to a pin 55 mounted on theframe 10. Spring 54 combines with the force of gravity to urge the outerend of the lever 43 downward. The pawl 45, of course, serves to rotatethe ratchet wheel 42 a limited distance each time the cam lever 43 ismoved upward by the cam 44, while the pawl 48 serves to prevent reversemovement of the ratchet wheel.

As a means of limiting the downward movement of the outer end of the camlever 43, a hand-operated bell crank lever 56 is journaled for freeoscillation on the shaft 14. The journal is a loose fit to permit slightmovement of the bell crank out of a plane perpendicular to shaft 14, thepurpose of which will be explained. The shape of this lever is moreclearly shown in FIG. 4. The handle portion of the bell crank lever 56carries a fixed detent 57 which engages teeth on a fixed quadrant 58,supported on the frame 10, which quadrant serves to maintain the lever56 in any desired position with relation to the cam lever 43. By movinglever 56 slightly out of its normal plane perpendicular to shaft 14, itshandle may be easily moved to various positions on the quadrant. Theoffset end 59 (FIG. 4) of bell crank lever 56 extends transversely intothe plane of oscillation of the cam lever 43. Thus when bell crank lever56 is placed in the position shown in FIG. 7 the offset 59 prevents camlever 43 from moving further downward after the two are in contact. Thislimits the number of teeth traversed by pawl 45 as lever 43 movesdownward, and consequently determines the number of degrees throughwhich the ratchet wheel 42 is moved during each oscillation of the camlever 43. This, in turn, determines the speed at which the cable 34 iswound on to the drum 35, and thus determines the speed at which theentire trencher moves along the ground and digs its trench.

The bell crank lever 56 serves an additional purpose, as clearlyillustrated in FIG. 8. When lever 56 is moved to the position shown inFIG. 8, the offset 59 forces the cam lever 43 to move upward welloutside the operational radius of the cam 44. During the latter part ofsuch upward movement the pin 46 contacts the inner end of slot 52 in thelink 51. Further upward movement of the cam lever 43 disengages pawl 45from the teeth of ratchet wheel 42, and transmits a longitudinalmovement to the link 51 in the direction of the arrow in FIG. 8. Thislongitudinal movement of the link is transmitted to the pointed end ofpawl 48, and disengages that pawl also from the teeth of the ratchetwheel 42. With both pawls out of contact with the ratchet wheel it ispossible for the wheel and shaft 14 to be freely rotated in eitherdirection so that the cable can be manually reeled in or reeled off ofdrum 35.

This manual rotation of the shaft 14 and its drum 35 is accomplished bya hand wheel 60 (FIG. 4), which is keyed to the shaft 14 but has slightlongitudinal movement thereon. A back-up washer 61 mounted on shaft 14serves to compress a coil spring 62 against the hub of hand wheel 60,and the hub in turn transmits this axial force to the hub of the bellcrank lever 56. This axial spring force serves to urge the detent 57 onthe bell crank lever 56 into contact with the teeth of the quadrant 58.

Operation With the digging unit 18 in the raised position 33, FIG. 1,and the guide or handle 36 also in the raised position 38, the trencheris moved to the location and position where the digging of the trench isto start. The handle latches 39 on the handle are released and thehandle is lowered to the position shown in FIG. 1. The ratchet Wheelmechanism is moved to the position shown in FIG. 8 to release the drum35 for free rotation with the shaft 14, and the cable is reeled oil? thedrum 35 and its outer end anchored by a stake driven into the ground orby any other type of ground anchor (not shown), so that the cableextends along the desired path of the trench to be dug. The cable isinserted into the slide 35 through the slot shown (FIG. 3).

The handle of the bell crank lever 56 is then moved to engage the properdetent on the quadrant 58 so that the oscillating movement of the camlever 43 will cause pawl 45 to traverse 2, 3, 4, 5 or 6 teeth as the camlever 43 moves downward during its oscillation. The setting will dependon the desired speed at which the trencher is to travel. This movementof the bell crank lever 56 permits the cam lever 43 to move downward andallow the pawls 45 and 48 to engage the teeth of the ratchet wheel 42.

The power unit 16 is started and the chain 22 on the digging unit beginsto move. Depth adjusting crank 32 is rotated to lower the digging unitinto ground contact. The starting of the engine causes cam 44 to revolvewith shaft 15 and to oscillate the cam lever 43. During each oscillationpawl 45 forces the ratchet wheel 42 to move through a limited number ofdegrees of rotation, thus rotating shaft 14 and its drum 35. Thetrencher is thus moved a very slight distance along the ground towardthe ground anchor during each oscillation of cam lever 43. The crank 32is further adjusted as the digging unit 18 digs into the ground untilthe proper depth of cut is attained. Thereafter the operator is notrequired to pay any particular attention to the trencher. It willcontinue its travel along the cable 34 and toward the ground anchor. Thespeed of the unit can be adjusted while it is in motion by simplychanging the position of the bell crank lever 56.

When the unit has traveled the entire distance to the ground anchor andthe cable 34 has been reeled in on the drum 35, the ground anchor isre-located and the cable unwound and again anchored to continue thedigging of the trench. If it is desired that the trencher follow anirregular path around a fixed object in the ground it is only necessaryto drive stakes along the desired path. The unit will follow that cablepath, knocking the ground stakes down as it goes.

Having described the invention with sufficient clarity to enable thosefamiliar with this art to construct and use it, I claim:

1. A winch propelled machine comprising: a wheeled chassis including arigid frame; a winch drum shaft journaled transversely in the frame; adriven shaft also jour naled transversely in the frame alongside butspaced from the drum shaft; a cam fixed on the driven shaft; a ratchetwheel fixed on the drum shaft; a pivotally mounted cam oscillated lever;a ratchet pawl carried by the lever for engaging the ratchet Wheel teethto partially rotate the ratchet wheel and the drum shaft each time thelever is oscillated by the cam; adjustable limiting means cooperatingwith said cam lever to selectively determine the extent of movement ofthe cam lever during each revolution of said cam; a holding pawlpivotally mounted on said frame for engagement with the ratchet teeth toprevent reverse movement of the ratchet wheel; a link connecting saidpawls, said link being slidably connected to at least one of said pawls,said slidable connection providing lost motion between said link and atleast one of said pawls whereby throughout the extent of said lostmotion connection both of said pawls engage said ratchet wheel duringoscillation of said cam lever by said cam, and means for moving theadjustable limiting means to a position in which both pawls are out ofengagement with said ratchet wheel; a winch drum fixed on the drumshaft; and a cable on the drum, its free end connectible to a groundanchor to pull the entire chassis along the ground toward the anchor asthe drum shaft is rotated.

2. The machine described in claim 1 and a rigid guide extendinglongitudinally forward from the front end of the chassis, and includinga cable slide at its forward end in substantial fore and aft alignmentwith the winch drum, and through which the anchored cable is reeled ontothe drum to guide the path of travel of the chassis.

3. The machine described in claim 2 wherein said cable guide comprises asubstantially U-shaped member having its free ends pivotally mounted onsaid frame; and locking means adapted to retain said guide in anelevated position to provide handle means to facilitate moving saidmachine from one location to another.

4. A winch propelled machine or the like comprising: a wheeled chassisincluding a rigid frame; a winch drum shaft and a power shaft journaledtransversely in said frame and spaced fore and aft therein; a drumcarried on and rotatable with the drum shaft; a cam fixed on the powershaft to rotate therewith; a ratchet wheel fixed on the winch shaft; acam lever having one end journaled on the winch shaft adjacent theratchet wheel and extending radially outward in the plane of said cam,to be oscillated thereby as the power shaft rotates; a ratchet wheelrotating pawl pivotally mounted on said cam lever in a position toengage the teeth of the ratchet wheel as the lever is oscillated by thecam; a bell crank lever journaled on said winch shaft adjacent to saidcam lever and having a portion thereof extending radially outwardly ofsaid shaft and having a portion offset laterally into the plane of saidcam lever, means to adjust the position of said bell crank angularlyabout said shaft to limit selectively the return movement of said camlever and the driving stroke of said ratchet pawl and thereby determinethe rotational speed of the winch shaft, said bell crank lever beingadjustable to an intermediate locking position to move said cam leverout of engagement with said cam and thereby stop rotation of said winchshaft; a holding pawl pivotally mounted on said frame for engagementwith the ratchet teeth to prevent reverse movement of the ratchet wheel;a link connecting said pawls, said link being slidably connected to atleast one of said pawls, said slidable connection providing lost motionbetween said link and at least one of said pawls of an extent such thatboth of said pawls are permitted to engage with said ratchet wheelthroughout the speed selective and intermediate locking positions ofsaid bell crank lever, said link being effective in another position ofsaid bell crank lever to disengage both of said pawls from said ratchetWheel and permit free rotation of said drum shaft; and a cable on thewinch drum, its free end adapted for connection to a ground anchor topull the entire machine along the ground toward the anchor as the winchdrum shaft is rotated.

References Cited in the file of this patent UNITED STATES PATENTS1,035,604 Kissel Aug. 13, 1912 1,168,091 Maughmer Jan. 11, 19161,484,841 Monahan Feb. 26, 1924 2,302,879 Neighbour et -al Nov. 24, 19422,519,075 Schmidt Aug. 15, 1950 2,571,579 Jones Oct. 16, 1951 2,599,741Bishman et al June 10, 1952 2,714,262 Malzahn Aug. 2, 1955 2,828,557Brown Apr. 1, 1958 FOREIGN PATENTS 148,796 Australia Oct. 27, 1952

